Conventionally, a 5-direction key operating device such as shown in FIG. 17 is known. In the main unit 500 of a portable telephone, a display section 501 such as a liquid crystal display device (LCD), and an operation section 502 in which various keys are arranged are disposed. The operation section 502 is configured by: a first portion consisting of cursor-movement keys 503 and an enter key 504; and a second portion consisting of ten keys, menu keys, and other keys 505. Among them, the first portion constitutes a 5-direction key operating device.
The five directions mean the upward, downward, rightward, and leftward directions (see triangular arrows in the figure), and the central direction. Usually, a cursor is moved among instruction displays on the display section 501 by operating keys of the forward, rearward, rightward, and leftward directions, i.e., the cursor-movement keys 503, and the instruction display to which the cursor is moved is determined by operating the central direction key, i.e., the enter key 504.
In the conventional 5-direction key operating device described above, the four cursor-movement keys 503 and the one enter key 504 are independently disposed, and hence there are problems in that a substantially large space is required for placing these keys, and that, when the keys are to be actually operated, the movement range of a specific finger is widened and the time period for the operation is correspondingly prolonged.
Therefore, a portable telephone or the like may be contemplated in which, as shown in FIG. 18, ten keys 631 and the like are formed integrally with a key sheet 630 made of silicon rubber or the like, and the assembly is attached to a predetermined position of a cover 610, and placed so as to be opposed to diaphragms 604 disposed on a printed circuit board 640.
In such a portable telephone, the 5-direction key operating device is configured by a 5-direction key 606 which is the largest key standing on the key sheet 630, and the diaphragms 604 which correspond thereto, and which are arranged in the shape of a cross.
In a design by those skilled in the art, as contacts on which the diaphragms 604 that are arranged in the shape of a cross in accordance with the 5-direction key 606 are to be placed, it is usual to design so that doughnut-shaped contacts such as shown in FIG. 19, i.e., first contacts 601 and second contacts 602 are disposed on the printed circuit board 640 and predetermined diaphragms 604 are placed thereon.
In this design, with respect to the space for disposing the diaphragm contacts, however, there is no choice other than that the minimum space is formed by placing the second contacts 602 to be placed as close as possible to the limit where the contacts are not in contact with each other.
Therefore, it is a first object of the invention to provide a 5-direction key operating device in which the structure of diaphragm contacts disposed on a printed circuit board is improved to allow five diaphragms to be disposed in a minimum space, and the five diaphragms can be operated by one button key.
It is also a second object of the invention to provide a 5-direction key operating device in which an operation space can be reduced, and desired one of information displayed on a display section can be selected and determined by a smooth key operation without causing an erroneous operation.